Tuesday, January 12, 2010

Where the Riders Are

Six months ago I highlighted a wonderful piece of work by Greater Greater Washington that took a look at ridership on the DC Metro. Well I finally got off my butt and did a similar thing for BART. I asked someone at BART who was affiliated with the recent rider survey for data on trips by station entry and exit.

Ask and ye shall receive; BART sent me an excel file containing average weekday origin/departure numbers for the spring and summer of 2009. I crunched the numbers a little and came up with the following

This map shows the number of people on each segment of track (between each station) on the BART system on an average weekday last spring/summer. You can also download a PDF showing the absolute numbers I came up with.

The map itself is probably not terribly surprising to anyone who is familiar with BART; the vast majority of its riders are on the tracks between downtown San Francisco and downtown Oakland.

I will be crunching more number in the future and making new illustrations of what I find.

One thing that immediately jumps out at you when looking at the raw data is the number of people who enter and exit out of the same station. You'd expect this number to be very small, and it is for most stations:

Richmond: 7
El Cerrito Plaza: 8
Ashby: 5
Coliseum: 7
Castro Valley: 6
South San Francisco: 5

But for a few stations the number is high. Like really high:

Concord: 2837
North Concord/Martinez: 3175
San Bruno: 3246
Millbrae: 5872

This striking ridership is all at stations far from the downtown core where most trips start or end. My guess is that these riders are taking advantage of the excursion fare because it's cheaper than the far to their destination. These riders may have a Fast Pass or some other means of entering and exiting the station at the other end of their trip, and so are committing some kind of high-class fare evasion to avoid paying the increasingly expensive cost of their commutes.

Curiouser and curiouser.


I received an email from the BART staff person who sent me the data for the above diagram:
The data sent to you previously was an average of various days from each of these months. There appears to be some sort of bug when selecting specific dates to come up with an average ... We are working on the bug and hope to have it resolved soon.
I'll be updating the above diagram again, and working on a few new ones in the near future.


david vartanoff said...

A bit surprised at the Orinda v Ashby ##--a couple years back Ashby was higher than Orinda. Would be nice to see the graphic crunched to show AM rush midday, OM Rush evening. My analysis says the Concord line is more highly used during rush much lighter off rush.

Michael D. Setty said...

This chart is way off.

I recall BART stating that transbay volume was around 180,000+/- riders daily, not the large numbers shown. And there are certainly not 200,000+ passengers through the Berkeley Hills tunnel.

The author needs to look at individual station Origin & Destination data, and determine the values for each link between each station. Granted, this is many more hours of work, but the results would still be useful.

Eric Fischer said...

Hmmm... a BART press release (http://www.bart.gov/news/articles/2009/news20091030.aspx) says that on October 30 during the Bay Bridge closure, there were 258,200 transbay trips. I think these numbers might be from one of those peak days instead of a typical day.

david vartanoff said...

Looked at April 09 station stats and find the fpllowing
Orinda 2685 Ashby 4342
Orinda thru PBP 29655
Richmond thru Ashby 33811
maybe a revision in the graphics?

Pedestrianist said...

Hey everyone, thanks for the comments. Regarding the number, there was a calculation error introduced somewhere between my excel spreadsheet and my email account. I'm not sure what exactly happened but these are the numbers as calculated in my excel spreadsheet, which seem to jibe much better with what you say above:

MB-SO 8648
SO-SB 19173
SB-SS 23727
SS-CM 28888
CM-DC 35087
DC-BP 47860
BP-GP 72657
GP-24 84413
24-16 98859
16-CC 109241
CC-PL 118337
PL-MT 118420
MT-EM 133133
EM-OW 157673
OW-12 97607
12-19 130170
19-MA 130101
MA-AS 52820
AS-BK 47431
BK-NB 33759
NB-EP 27427
EP-EN 20181
EN-RM 6795
MA-RR 73227
RR-OR 64338
OR-LF 58822
LF-WC 52238
WC-PH 41268
PH-CN 27628
CN-NC 16438
NC-WP 11870
OW-LM 54393
LM-FV 84078
FV-CL 76123
CL-SL 66768
SL-BF 55917
BF-HY 30117
HY-SH 24330
SH-UC 19817
UC-FM 13263
BF-CV 18520
CV-ED 14611
12-LM 32945

Pedestrianist said...

@ David Vartanoff
The numbers on the diagram above represent the number of people on the rails for each track segment. It's difficult to see the entry/exit numbers for each station by looking at this diagram. So the wider line at Orinda doesn't mean more people use that station, just that more pass through it.

@Michael D. Setty
What you describe is exactly how I crunched the numbers. I'm not sure where the incorrect data set that I used for the diagram came from, but I will fix it soon. Hopefully the data above matches your expectations.

david vartanoff said...

I looked at your segment ## but they contradict the data I cited. So I still believe that total riders boarding between Richmond and Ashby are greater that Pittsbur thru Orinda. 33,811 to 29,655. This is a critical difference because it underlines the light usage east of the hills-- as a rider complained he has to stand from Montgomery to Rockridge evenings after rush. Given the various plans to piss away millions on further extensions into the sprawlburbs, the picture of the urban core usage is unfortunate.
When the bridge was out we witnessed the trains filling up east of the hills.

Pedestrianist said...

@David Vartanoff

From the raw data, I can see 32,507 trips starting at Richmond through Ashby stations and 34,185 trips ending at those stations. Those numbers double-count trips that started and ended at one of those station (there are 6,869 such trips in the data).

Where are you numbers from and what is meant by Richmond through Ashby/Orinda through Pittsburg? Are those entries and exits?

david vartanoff said...

data are from BART April 2009 Station Entry Exit Matrices received from BART.
The Richmond thru Ashby # was total entries along this route, PBP thru Orinda same. Point was to aggregate boarding riders in a large service area. So from where I sit, the 'line' from Maca to Ashby should have been as thick as Maca to RR, and thicker than RR to Orinda. I have been particularly interested in these sorts of data because I object to spending billions for low usage routes to sprawl--BART to San Jose, eBART to xxx the disastrous SFO route which could have been cheaper AND better and believe dense usage areas deserve better service. Given that riders east of the hills pay much less per mile and get the fabled "one seat ride" evenings and Sundays in mostly empty trains, I favor a redesign of service patterns FWIW I also believe in 24/7 transit in cities.

Pedestrianist said...

I've updated the graphic; have at it y'all!